Desert climate

Deserts are very dry lands.

They do not get much rain. When it does rain, the ground dries up fast. This happens because the sun is very strong.

Some deserts are very hot. These places have lots of sun. They can be the hottest spots on Earth.

Other deserts can be cold. These places have cold winters. They are often near big mountains.

Some deserts are even in the icy poles. The air there is very cold and dry. It is a wild place to see.

Deserts are very dry places. They cover 14.2% of the land on Earth.

In a desert, water evaporates very fast. This means water turns into gas and goes into the air. This happens because there is much more evaporation than rain.

There are two main types of desert climates. The first is the hot desert climate. These are found in many places, like North Africa. They have intense sunshine and high pressure. This high pressure keeps clouds away.

Hot deserts can be very hot. Death Valley in the United States has a huge heat record.

At night, the sky is clear. This lets heat escape, so it can get cold.

The second type is the cold desert climate. These often have dry summers and cold winters.

Many cold deserts are near big mountains. The mountains block rain from reaching them. The Gobi Desert in Mongolia is a cold desert.

Some deserts are even at the icy poles. The air there is so cold that most water stays frozen.

A desert climate is a very dry place on Earth. These areas are known as arid climates. They cover 14.2% of all the land on our planet.

In these places, water disappears faster than it arrives. This happens because evaporation is much higher than the amount of rain.

The ground is often sandy, rocky, or bare. Because there is so little moisture, any rain that falls evaporates very quickly. This makes deserts some of the driest places we can find.

Scientists use a system called the Köppen climate classification to group these areas. They use two main labels: BWh for hot deserts and BWk for cold deserts.

To tell them apart, they look at the average yearly temperature. If the temperature is above a certain line, it is a hot desert. If it is below that line, it is a cold desert.

They also use a special math rule called a precipitation threshold. This rule looks at how much rain falls and when it falls during the year. If the rain is less than half of this threshold, the area is a desert.

Hot deserts are often found in the subtropics. In these spots, air sinks down from high above.

This sinking air creates high pressure. High pressure clears away clouds and brings intense sunshine. Because there are no clouds, the sun beats down very hard. This makes hot deserts some of the sunniest places on Earth. Some of these areas, like the Sahel, can even have very little rain due to this extreme heat.

Hot deserts can reach incredible temperatures.

In Death Valley in the United States, the heat has reached record levels. Some tropical deserts, like Dallol in Ethiopia, stay very hot all year long. However, the nights can still be chilly. Because the sky is so clear, heat escapes into space very easily. This can cause temperatures to drop to freezing at night.

In the Atacama Desert of Chile, it is so dry that rain is very rare.

Cold deserts work a bit differently. They often have warm summers but very cold winters.

Many cold deserts sit at high altitudes or behind big mountains. These mountains create what is called a rain shadow. The mountains block moisture from the wind from reaching the land. The Gobi Desert in Mongolia is a famous example of this.

Other cold deserts include the Great Basin in North America and the Patagonian Desert in Argentina.

A desert climate, also known as an arid climate, is a dry environment defined by a severe imbalance. In these regions, the rate of evaporation exceeds the amount of precipitation received.

This means water leaves the ground faster than it can be replaced by rain or snow. Because of this, desert surfaces are often bald, rocky, or sandy. These surfaces hold very little moisture and cause any small amount of rainfall to evaporate almost immediately. Today, these climates cover 14.2% of the Earth's total land area.

Scientists use the Köppen climate classification system to organize these dry regions. This system identifies two specific subtypes: hot desert climates (BWh) and cold desert climates (BWk).

To distinguish between them, researchers use an isotherm, which is a line representing a specific mean annual temperature. If a location's temperature stays above this line, it is classified as a hot arid subtype. If the temperature falls below the line, it is a cold arid subtype. This distinction helps scientists understand the different thermal environments found in dry zones.

To officially label a place as a desert, scientists must calculate a precipitation threshold. This mathematical process begins by multiplying the average annual temperature in degrees Celsius by 20. Next, they add a specific number based on when the rain falls. If 70% or more of the rain occurs during the high-sun summer months, they add 280. If the rainfall is split more evenly, between 30% and 70%, they add 140. If less than 30% falls in summer, they add 0. If an area's actual annual precipitation is less than 50% of this calculated threshold, it is classified as a BW desert climate.

Hot desert climates (BWh) are typically found in the subtropics between 20° and 33° north and south latitudes.

These areas are shaped by stable, descending air and high pressure located high in the atmosphere. As this air sinks, it clears away clouds and prevents atmospheric disturbances or rain-bearing fronts from forming. This creates intense sunshine and scorching heat. Hot deserts are found on every continent except Antarctica. They include massive regions like the Sahara in North Africa, the Arabian Desert in West Asia, and the Great Victoria Desert in Australia.

These hot regions are defined by extreme temperature fluctuations and intense solar radiation.

During the summer, midday readings can reach very high levels. The world's absolute heat records, which exceed 50°C, are generally found in these hot deserts. Death Valley in the United States holds a record for being one of the highest temperatures ever measured on Earth. Some tropical deserts, such as Dallol in Ethiopia, maintain very high annual averages, sometimes reaching nearly 40°C. However, because the skies are so clear, night-time temperatures can drop to freezing due to radiation loss.

Cold desert climates (BWk) operate under different geographic conditions.

These climates usually feature warm or hot summers, but they are characterized by cold, dry winters. They are often found at higher altitudes than hot deserts or in temperate zones between 30° and 40° latitude. A common cause for these deserts is the rain shadow effect. This happens when high mountains block moisture-carrying winds from reaching the land. The Patagonian Desert in Argentina is a prime example, as it is bounded by the Andes mountains.

Other notable cold deserts exist across the globe in various landscapes.

The Gobi Desert in China and Mongolia experiences freezing winters despite its summer heat. In North America, the Great Basin Desert and the Columbia Plateau represent this climate type. Even more extreme are the polar deserts found in the Arctic and Antarctic regions. While these areas are classified as polar climates because their summer temperatures stay below 10°C, they share desert traits like barren terrain and hypersaline lakes.

These extreme environments show how aridity can exist in many different forms across our planet.